1. Field of the Invention
The present invention relates to the lining of arcuate chambers. More specifically, it relates to a novel method and apparatus for attaching a lining to an arcuate chamber that reduces the amount of stress on the lining material during and after the installation process. Even more specifically, it relates to a lining method and apparatus for sheet material wherein one end is fastened down to the chamber wall, compressive force is applied to bow the sheet such that it is in substantially complete contact with the wall of the chamber, and the compressive force is locked into the sheet by welding before removing the force applicator. Additionally, the successive sheets are overlapped to completely cover the surface of the chamber. More generally, the present invention serves as an improvement over existing methods for sheeting or "wallpapering" the inside of a cylindrical tank or column to protect the shell of the structure from corrosive, frictional, or other types of degradation.
Thus it can be seen that the potential fields of use for this invention are myriad and the particular preferred embodiment described herein is in no way meant to limit the use of the invention to the particular field chosen for exposition of the details of the invention.
A comprehensive listing of all the possible fields to which this invention may be applied is limited only by the imagination and is therefore not provided herein. Some of the more obvious applications are mentioned herein in the interest of providing a full and complete disclosure of the unique properties of this previously unknown general purpose article of manufacture. It is to be understood from the outset that the scope of this invention is not limited to these fields or to the specific examples of potential uses presented hereinafter.
2. Description of the Prior Art
There are many applications where the main body or substrate of a chamber is covered by a sheeting or protective surface. An example of such an application is the interior of absorber towers, flue gas desulfurization ductwork and the like. The substrate material, carbon steel for instance in the case of an absorber tower, needs to be covered with a protective HNA (High Nickel Alloy) sheeting or "wallpaper" over the interior surface of the tower to protect the material from the corrosive gasses generated by the process. Presently, this is accomplished in two different, yet basically similar ways in which the sheet is supported at the proper location by clips or the like and then plug welded (usually two to three inches center to center) to the substrate. The sheet is then manually pushed in and spot tacked around its outer edges. The horizontal and vertical seams are then welded. These types of methods leads to a large amount of stress distributed about the protective sheet, which in turn can shorten the useful lifespan of the sheathing, requiring expensive replacement or repair. Additionally, this process is very labor intensive and still does not provide the final results required for (FGD) projects. The present invention seeks to address the flaws inherent in this standard method of installation by providing an alternative method of attaching or fitting the HNA sheeting to the carbon steel substrate. One side of the HNA sheeting is held in place and a vertical weld is made along a seam. Compressive force is then applied to the opposite end of the sheeting, distal from the welded end, and this force causes the sheet to "bow" up against the substrate. Keeper welds, which trap the compressive force into each sheet, are applied prior to removing the force applicator. The sheet can then be fixed in place through seam welds about its periphery and no plug welds are required. During a search at the U.S. Patent and Trademark Office, a number of patents were uncovered that relate to this field and they are discussed hereinafter:
U.S. Pat. No. 3,702,058 issued to Seratino De Corso et al. on Nov. 7, 1972 discloses a double wall combustion chamber. In this, the combustion chambers are spaced angularly and concentrically to one another. This is dissimilar from the present invention in that no sheeting or "wallpapering" of the wall substrate is shown.
In U.S. Pat. No. 3,595,550 issued to Robert Greer on Jul. 27, 1971 there is disclosed a furnace lining. In this patent, there are a pair of refractory tiles spaced apart to provide an airgap between them. These tiles are held by support members inwardly from the furnace casing or framework. Contrast this to the present invention wherein the HNA or other protective sheathing material is pressed up to be substantially completely in contact with the substrate before being fixed in place.
U.S. Pat. No. 4,875,339 issued to Neil S. Rasmussen et al. on Oct. 24, 1989 discloses a combustion chamber liner insert. The inserts are placed in the combuster liner air admission hole. This is clearly dissimilar from the present invention in that there is no teaching of lateral compression of sheeting material to bow it to the inner surface of an arcuate chamber wall.
In U.S. Pat. No. 4,489,920 issued to William R. Jones on Dec. 25, 1984 there is disclosed a hot zone chamber wall arrangement. A plurality of ceramic tiles include beveled edges to interengage one another. Support panels hold the tiles in place. As in the Rasmussen patent above, however, there is no teaching of the lateral compression directed at the lining sheet.
Lastly, U.S. Pat. No. 5,139,239 issued to Kenneth T. Eccleston discloses a lining for molten metal handling vessels. Removable material is placed on the surface of the vessel and an expendable slurry lining is applied over that. The removable lining can then be taken out, or it may be heat consumable. Contrast this to the present invention wherein the sheet or lining material is substantially in complete contact with the substrate material to which it is being applied. on
As will be seen, the simplicity and effectiveness of my invention is not rivaled in the prior art.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.